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Date:      Thu, 10 Dec 2009 10:59:20 +0100
From:      Ivan Voras <ivoras@freebsd.org>
To:        Robert Watson <rwatson@freebsd.org>
Cc:        freebsd-hackers@freebsd.org, Linda Messerschmidt <linda.messerschmidt@gmail.com>
Subject:   Re: UNIX domain sockets on nullfs still broken?
Message-ID:  <9bbcef730912100159s49704c18o1225d060c422b273@mail.gmail.com>
In-Reply-To: <alpine.BSF.2.00.0912100943450.23303@fledge.watson.org>
References:  <20091130142950.GA86528@logik.internal.network>  <hf0lle$5mk$1@ger.gmane.org> <20091130150127.GA82188@logik.internal.network>  <hf0ngp$cpb$1@ger.gmane.org> <237c27100912010722g2f6c4647ga82370284bc26e20@mail.gmail.com>  <alpine.BSF.2.00.0912100943450.23303@fledge.watson.org>

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2009/12/10 Robert Watson <rwatson@freebsd.org>:
>
> On Tue, 1 Dec 2009, Linda Messerschmidt wrote:
>
>> On Mon, Nov 30, 2009 at 10:14 AM, Ivan Voras <ivoras@freebsd.org> wrote:
>>>>
>>>> What's the sane solution, then, when the only method of communication
>>>> is unix domain sockets?
>>>
>>> It is a security problem. I think the long-term solution would be to add
>>> a
>>> sysctl analogous to security.jail.param.securelevel to handle this.
>>
>> Out of curiosity, why is allowing accessing to a Unix domain socket in a
>> filesystem to which a jail has explicitly been allowed access more or less
>> secure than allowing access to a file or a devfs node in a filesystem to
>> which a jail has explicitly been allowed access?
>
> (I seem to have caught this thread rather late in the game due to being on
> travel) -- Ivan is wrong about nullfs, it's broken due to a bug, not a
> feature, and that bug is not present when using a single file system.  He's
> thinking of unionfs semantics, where if it worked it would be a bug.  :-)

You have a point there. I was actually thinking more of sysvshm -
which doesn't have anything to do with any of the issues here - but
has some of the same properties (and is also used by databases - e.g.
postgresql, which I'm using daily so it sort of cross-linked). The
reason I'd like the nullfs barrier kept is that it (like shm) is used
for IPC, and in this case, IPC across different jails (though a file
system itself also be used so...). It's not a big issue - I'll also
accept that it's the operator's fault if he doesn't know sharing file
systems will also share sockets and fifos on it...


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